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Abiotic Factor – A nonliving condition or parameter (soil, sunlight, climate, landscape, geology, aspect, latitude, water) that influences or affects an ecosystem and the organisms in it.

Acidification – The process of soil becoming more acid as basic cations leach from the soil, leaving acidic cations behind. This is a natural process, but can be accelerated by human activities.

Actinomycetes – Thread-like bacteria that give soil its “earthy” odor.

Additions – The process of depositing new components/materials into the soil materials, either from above, or moved in with groundwater.

Adsorb (adsorption) – Attachment of ions to mineral and organic matter surfaces in soil.

Aerobic – In the presence of oxygen (O2); requiring oxygen.

Agroforestry – Any type of multiple cropping land use that entails complementary relations between tree and agricultural crops and produces some combination of food, fruit, fodder, fuel, wood, mulches, or other products.

Alfisols – Moderately leached soils often found in temperate forests—generally east of the Mississippi.

Alley Cropping – Growing vegetable, grain and/or forage crops between rows of trees.

Alluvium – Sediments deposited by running water of streams and rivers. It may occur on terraces well above present streams, on the present flood plains or deltas, or as a fan at the base of a slope.

Ammonia – Form of nitrogen (NH3) that converts in water to form plant-available ammonium (NH4+).

Ammonification – The conversion of organic nitrogen to ammonium (NH4+) by the action of decomposers (bacteria).

Anaerobic – In the absence of molecular oxygen (O2); not requiring oxygen.

Andisols – Soils formed in volcanic ash—Pacific Northwest, Japan.

Angiosperm – Flowering plant in which the mature seed is surrounded by the ovule (such as an apple, oak, daisy, grasses).

Anion – Negatively charged ions (NO3−, Cl−, SO4−2).

Anion exchange capacity (AEC) – Quantity of positive charges on surfaces of mineral and organic matter that attracts anions.

Antibiotic – Organic compound that in low concentrations is inhibitory to other organisms.

Arable – Land that is capable of sustaining crops, where production is practical and economically feasible.

Arbuscule – Highly branched structure formed by endomycorrhizal fungi within root cortical cells.

Archaea – Prokaryotic single-celled microorganisms some of which live in extreme environments.

Aridisols – Desert soils—desert areas worldwide.

Arthopod – An invertebrate animal having an exoskeleton, a segmented body, and jointed appendages including insects, arachnids, and crustaceans.

Assimilation – Uptake or utilization of an element by an organism.

Association – A map unit composed of two or more soil series occurring together in a characteristic, repeating pattern.

Atmosphere – The envelope of gases surrounding the earth (the air).

Bacterium (Plural: Bacteria) – Prokaryotic single-celled microorganism common in soil that lacks a nucleus or other membrane-bound internal structures.

Base Saturation – Proportion of the cation exchange capacity occupied with basic cations (Ca+2, Mg+2, K+).

Berlese Funnel – Method of extracting small animals from soil by use of a heat/light source.

Best Management Practice (BMP) – Any of a group of practices that conserve soil and water resources.

Biodiversity – The degree of variation of life forms within a given species, ecosystem, biome, or an entire planet. Often used as a measure of health of an ecosystem.

Biological Nitrogen Fixation – Conversion by prokaryotic microorganisms of molecular dinitrogen (N2) from the atmosphere to ammonia for organismal use.

Biomass – Mass of living tissue.

Biome – A large geographic region with similar environment and distinctive a plant and animal community.

Bioremediation – The use of biological agents, such as bacteria or plants, to remove or neutralize contaminants from polluted soil or water.

Biosolids – Sludge (municipal treatment plant solids) that has been further treated, tested, and determined to be safe for land application.

Biosphere – The regions of the surface and atmosphere of the earth or other planet occupied by living organisms (the biota, or living organisms).

Bioturbation – Mixing of the soil by organisms—worms, ants, moles, tree roots.

Black Blizzard – A colloquial term for a dust-storm in the dust bowl of the south-central United States.

Brownfield – Abandoned or under­used industrial and commercial facilities or sites available for re-use or redevelopment.

Buffer – Ability of the soil to replace ions in soil solution removed by plant uptake or other loss processes

Buffers (Buffer Strip) – Strips of perennial plants, such as grasses, along borders of fields or water bodies.

Bulk Density – The mass of dry soil per unit bulk volume. The value is expressed as megrams per cubic meter, Mg m-3.

Cairns – Human-made pile or stack of stones set up as a landmark or memorial.

Capillarity – Combination of the attractive forces between a water molecule and a surface (adhesion) and the attractive forces between water molecules (cohesion).

Capillary Zone or Fringe – Zone, just above the water table or zone of saturation, where water is held in the soil against the force of gravity by the capillary attraction of water to the soil particles. Water content in the zone is highest near the water table and decreases with distance above the water table.

Carrying Capacity – A measure of the ability of the soil to support tractors and other vehicles.

Cash Crop – A crop, such as tobacco, grown for direct sale rather than for livestock feed.

Cation – Positively charged ions (Ca+2, H+, Al+3).

Cation Exchange Capacity (CEC) – Quantity of negative charges on surfaces of mineral and organic matter that attracts cations.

Chlorophyll – Molecule that allows organisms, including plants, to use sunlight as an energy source.

Chroma – The relative purity, strength, or saturation of a color; directly related to the dominance of the determining wavelength of the light and inversely related to grayness; one of the three variables of color. See also Munsell color system, hue, and value.

CLORPT – Acronym to helpt students remember the factors of soil formation: CLimate, Organisms, Relief, Parent material, and Time.

Colluvium – Unconsolidated, unsorted earth material being transported or deposited on sideslopes and/or at the base of slopes by mass movement (e.g., direct gravitational action) and by local, unconcentrated runoff.

Complex – A map unit composed of two or more soil series intimately intermixed geographically that they cannot be separated at the mapping scale.

Conidium (Plural: Conidia) – Resting structures of actinomycetes and fungi.

Conservation Tillage – Any tillage sequence, the object of which is to minimize or reduce loss of soil and water; operationally, a tillage or tillage and planting combination which leaves a 30% or greater cover of crop residue on the surface.

Consistence – The attributes of soil material as expressed in degree of cohesion and adhesion or in resistance to deformation or rupture.

Consociation – A map unit dominated by the named soil series while adjacent soils have properties and management requirements similar to the named soil.

Cover Crops – Close-growing crop, that provides soil protection, seeding protection, and soil improvement between periods of normal crop production, or between trees in orchards and vines in vineyards. When plowed under and incorporated into the soil, cover crops may be referred to as green manure crops.

Critical zone – Soil or pedosphere—the zone or area at the surface of the earth where life (the biosphere), water (the hydrosphere), minerals (the lithosphere), and air (the atmosphere) intersect and interact.

Crop – A plant used for human purposes, such as food, fiber, construction material or fuel.

Crop Rotation – A planned sequence of crops growing in a regularly recurring succession on the same area of land, as contrasted to continuous culture of one crop or growing a variable sequence of crops.

Cryic – average annual soil temperature soil is near freezing, lacks permafrost

Cyanobacteria – Bacteria that use sunlight as an energy source, may use n2 from the atmosphere as a nitrogen source, and which evolve molecular oxygen (O2) (formerly called blue-green algae).

Deficiency – When a nutrient is not plentiful enough to allow for proper growth.

Deforestation – The permanent removal of trees until less than 10% of the forested land remains.

Denitrification – In the absence of molecular oxygen (O2), some bacteria can use oxidized nitrogen (nitrate and nitrite) as a terminal electron acceptor and produce dinitrogen gas (N2).

Desertification – Land degradation where the land area is becoming increasing dry and inhospitable to plants and animals.

Desorb (desorption) – Detachment of ions from mineral and organic matter surfaces to the soil solution.

Detailed reconnaissance soil map – A reconnaissance map on which some areas or features are shown in greater detail than usual, or than others.

Detailed soil map – A soil map on which the boundaries are shown between all soils that are significant to potential use as field management systems.

Detention Basins – Basins constructed to contain storm water runoff, especially from construction sites, to allow sediments to settle prior to runoff water entering surface waterways such as streams and rivers.

Detritivores – Organisms that eat detritus (organic matter) that is added to the soil as organisms die

Diatom – Plant-like protists (algae) that have a siliceous cell wall and can use sunlight as an energy source.

Dichotomous Key – A key used to classify an item in which each stage presents two options, with a direction to another stage in the key, until the lowest level is reached.

Dissolve – Transformation of a compound into its component cations and anions.

Diurnal – Any pattern that recurs daily.

Diversion – A structure or barrier built to divert part or all of the water of a stream to a different course.

Dynamic – A system that is active, and constantly changing due to many interactions among components.

Earthworm – Segmented worm that burrows through soil leaving passages for rapid air and water movement.

Ecology – Study of how organisms relate to each other and to their environment.

Ecosystem – A system formed by the interaction of a community of organisms with their environment.

Ectomycorrhiza (Plural: Ectomycorrhizae) – Association (usually beneficial) between fungi and plants that forms a fungal sheath on the outside of the root tip and hyphae among cortical cells of the root (adjective form is ectomycorrhizal).

Effluent – Liquid portion of wastes removed during the wastewater treatment process,

Eluviation – The translocation (removal) of soil material (either suspended or dissolved in water filling soil pores) from a layer (soil horizon) to a deeper horizon. Usually, the total loss of material from the soil profile to groundwater is called “leaching.”

Endosaturation – The soil is saturated with water in all layers from the upper boundary of saturation to a depth of 200 cm or more from the mineral soil surface. See also episaturation.

Entisols – Soils with little or no morphological (horizon) development—beaches, sand dunes, and floodplains.

Entrainment – Particles caught and transported in the flow of water or wind,

Eolian – Pertaining to earth material transported and deposited by the wind including dune sands, sand sheets, loess, and parna.

Epiphyte – A plant that grows on another plant and depends on it for support but not food (non-parasitic). Epiphytes get moisture and nutrients from the air or from small pools of water that collect on the host plant. Spanish moss and many orchids are epiphytes. This is an example of commensalism.

Episaturation – The soil is saturated with water in one or more layers within 200 cm of the mineral soil surface and also has one or more unsaturated layers with an upper boundary above 200 cm depth, below the saturated layer(s) (a perched water table). See also endosaturation.

Erosion – (i) the wearing away of the land surface by rain or irrigation water, wind, ice, or other natural or anthropogenic agents that abrade, detach and remove geologic parent material or soil from one point on the earth’s surface and deposit it elsewhere; (ii) the detachment and movement of soil or rock by water, wind, ice, or gravity.

Eukaryotic – Organisms having more complex cell structure including membrane-bound internal organelles.

Exchange Sites – Charged sites on the surfaces of soil materials such as clay or organic matter that can store nutrients in ion form.

External drainage – Related to how water moves on the landscape due to slope and landscape position.

Fallow – Tilled but not planted to a crop during the growing season.

Fauna – Animal life.

Fluvial – Deposited by rivers.

Fungus (Plural: Fungi) – Large group of eukaryotic organisms that contain a rigid cell wall and include filamentous microorganisms, mushrooms, smuts, rusts, yeasts, and molds.

Gelic – average annual soil temperature is near or below freezing, has permafrost

Gelisols – Soils with permafrost—tundra, Alaska, Siberia, Northern Canada.

Geophagy – Deliberately ingesting clay or soil.

Geosmin – Organic compound that is volatile and gives soil its “earthy” odor.

Glaciofluvial Material – Material moved by glaciers and subsequently sorted and deposited by streams flowing from the melting ice. The deposits are stratified and may occur in the form of outwash plains, deltas, kames, eskers, and kame terraces.

Gley – Developed under conditions of poor drainage resulting in reduction of iron and other elements and in gray colors and mottles. (Not used in current U.S. system of soil taxonomy; also, a soil condition resulting from prolonged soil saturation, which is manifested by the presence of bluish or greenish colors through the soil mass or in mottles (spots or streaks) among the colors. Gleying occurs under reducing conditions, by which iron is reduced predominantly to the ferrous state.

Grassed Waterway – A natural or constructed waterway, usually broad and shallow, covered with grasses, used to conduct surface water from or through cropland.

Gravitational Water – Water that moves into, through, or out of the soil under the influence of gravity.

Green Roof – A roof of a building that is partially or completely covered with vegetation and a growing medium (soil), planted over a waterproof membrane.

GROUNDWATER – The zone where all of the pores in the soil are filled with water and water will flow due to gravity. The water table refers to the top of this zone.

Gully – A channel resulting from erosion and caused by the concentrated but intermittent flow of water usually during and immediately following heavy rains. Deep enough to interfere with, and not to be obliterated by, normal tillage operations.

Gymnosperms – Plants whose seeds are not enclosed in an ovule (like a pine cone). Gymnosperm means “naked seed.”

Heterocyst – Specialized cells of cyanobacteria where biological nitrogen fixation occurs.

Hidden Hunger – Level of nutrient deficiency that reduces plant yield without observable visual deficiency symptoms.

Histosols – Organic soils—very wet areas, parts of FL, MN, AK, MI, ME, NC.

Horizon – A layer of soil or soil material approximately parallel to the land surface and differing from adjacent genetically related layers in physical, chemical, and biological properties or characteristics, such as color, structure, texture, consistency, kinds and number of organisms present, degree of acidity or alkalinity, etc.

Horizon, (Master ) – Major soil horizons designated by a capital letter. Each master horizon has a single dominant characteristic i.e. O horizon is dominated by organic matter, C horizon is parent material.

Horizon, (Subordinate ) – Horizons that have a specific property that allows them to be further subdivided.

Hue – A measure of the chromatic composition of light that reaches the eye; one of the three variables of color. See also Munsell color system, chroma, and value, color.

Humus – Dark, organic fraction of soil that has been well decomposed and is relatively stable.

Hydraulic Conductivity – Amount of water (liquid) that can move through a unit area of soil in a unit of time (see permeability).

Hydrophobic Soils (Hydrophobicity) – The tendency for a soil particle or soil mass to resist hydration, usually quantified using the water drop penetration time test.

Hydrophyte – Plants that are adapted to grow in water or wetlands.

Hydrosphere – All the waters on the earth’s surface, such as lakes and seas, and sometimes including water over the earth’s surface, such as clouds (the water).

Hyperthermic – average annual soil temperature is high than thermic, sometimes referred to as the citrus belt

Hypha (Plural: Hyphae) – Long filaments or threads that are part of the structure of fungi and actinomycetes.

Illuviation – The translocation (deposition) of soil material in a soil horizon that has been removed from another horizon by eluviation; usually from an upper to a lower horizon in the soil profile.

Immobilization – Conversion of plant available nutrients to an organic form which is unavailable to plants.

Inceptisols – Weakly developed soils—almost anywhere.

Infiltration – The entry of water into soil.

Integrated Pest Management (IPM) – A system that uses a combination of biological, cultural, mechanical, chemical, and regulatory tools to control pests such as weeds and insects.

Internal drainage – Related to how water moves through the soil due texture, structure and consistence.

Ion Exchange – The interchange between an ion in solution and another ion in the boundary layer between the solution and surface of a charged material such as clay or organic matter.

Irrigation – The intentional application of water to the soil, usually for the purpose of crop production.

Isomorphic Substitution – The replacement of one element for another in a mineral structure or crystal without disrupting the mineral.

Lacustrine – Deposited in lakes.

Land Capability Class – One of the eight classes of land in the land capability classification of the usda-nrcs, distinguished according to the risk of land damage or the difficulty of land use.

Leaching – The process of removal (loss) of dissolved soil materials (that are in solution in water filling soil pores), such as nutrients, out of the soil into the parent material and/or groundwater below it.

Lithosphere – The solid, outermost surface of the earth (the rocks).

Loess – Material transported and deposited by wind and consisting of predominantly silt-sized particles.

Losses – The process of removal of soil materials by various pathways; i.e., leaching, erosion.

Luxury Consumption – Ability of plants to absorb nutrients at levels above that needed for optimum plant growth and yield.

Macronutrient – Essential elements (N, P, K, Ca, Mg, S) nutrient found in plants in the highest amounts.

Macroorganism – Organism larger than 2 millimeters.

Macrophyte – Wetland vegetation that may grow above the water surface (emergent), remain below the water surface (submergent), or float on top of the water.

Macropores – Large pores responsible for preferential flow and rapid, far-reaching transport.

Map Unit – (i) a delineation identified by the same name in a soil survey that represent similar soil and landscape areas; (ii) a loose synonym for a delineation.

Massive – A structureless soil condition where there are no aggregates and appears cohesive. No discernible planes of weakness exist in massive material.

Massive-Rock Controlled Fabric – A structureless soil condition where the material has retained its rock fabric but has been weathered to the point where it can be easily excavated. Material often breaks apart along planes of weakness related to the original rock fabric .

Matrix Color – The dominant color of the horizon, or layer.

Mesic – average annual soil temperature is well above freezing, sometimes referred as the corn belt

Mesoorganism – Organism between 0.1 and 2 millimeters.

Micronutrient – Essential elements (Cl, Fe, B, Mn, Zn, Cu, Ni, Mo) nutrient found in plants in the lowest amounts. Also referred to as minor elements.

Microorganism – Organism smaller than 0.1 millimeters (100 micrometers).

Micropores – Pores that are sufficiently small that water within these pores is considered immobile, but available for plant extraction, and solute transport is by diffusion only.

Mineralization – Conversion of an element from an organic to an inorganic form.

Mite – Small, eight-legged invertebrates, many of which are microscopic.

Mollisols – Grassland soils—the Great Plains, Russian steppes.

Munsell color system – A color designation system that specifies the relative degrees of the three simple variables of color: hue, value, and chroma. For example: 10YR 6/4 is a color (of soil) with a hue = 10YR, value = 6, and chroma = 4. See also chroma, hue, value, color.

Mycorrhiza (Plural: Mycorrhizae) – Literally means “fungus roots.” the association, usually beneficial, of specific fungi with the roots of higher plants (adjective form is mycorrhizal).

Nematode – Nonsegmented worm, often microscopic. Some are parasitic on plants but many are normal soil inhabits that feed on fungi and bacteria.

Nitrate – Plant-available form of nitrogen (NO3–).

Nitrification – Biological oxidation (loss of electrons) of ammonium to nitrite and nitrate.

Nitrogen Cycle – Describes the conversion of dinitrogen gas (N2) from the atmosphere through microbes, plants, and animals to soil transformations and back to atmospheric dinitrogen gas. Important microbial processes include biological nitrogen fixation, mineralization, nitrification, and denitrification.

Nitrogenase – Active enzyme involved in biological nitrogen fixation that converts dinitrogen gas (N2) into ammonia (NH3).

No-till – Practices by which a crop is planted directly into the soil with no primary or secondary tillage. The surface residue is left virtually undisturbed except where the seed is planted.

Nutrient – An element essential to living organisms.

Ombrotrophic – A bog, soil or vegetation that receives all moisture from atmospheric sources such as precipitation rather than groundwater, springs, or rivers.

Organic Materials – Soil materials that are saturated with water and have 174 g kg-1 or more organic carbon if the mineral fraction has 500 g kg-1 or more clay, or 116 g kg-1 organic carbon if the mineral fraction has no clay, or has proportional intermediate contents, or if never saturated with water, have 203 g kg-1 or more organic carbon.

Oxisols – Very weathered soils of tropical and subtropical environments—Puerto Rico and Hawaii and other tropical areas such as Brazil and Southeast Asia.

Pathogen – Any disease-producing agent, especially a virus, bacterium, or other microorganism.

Ped – A unit of soil structure such as a block, column, granule, plate, or prism, formed by natural processes (in contrast with a clod, which is formed artificially).

Pedosphere – That shell or layer of the earth in which soil-forming processes occur. It is where the lithosphere, biosphere, hydrosphere and atmosphere intersect (the soil).

Permaculture – An agricultural system or method that seeks to integrate human activity with natural surroundings so as to create highly efficient self-sustaining ecosystems.

Permafrost – Permanently frozen subsoil, occurring throughout the polar regions and locally in perennially frigid areas.

Permeability – (i) The ease with which gases, liquids, or plant roots penetrate or pass through a bulk mass of soil or a layer of soil. Since different soil horizons vary in permeability, the particular horizon under question should be designated. (ii) The property of a porous medium itself that expresses the ease with which gases, liquids, or other substances can flow through it, and is the same as intrinsic permeability k.

Phytoremediation – A bioremediation process the uses plants to remove or neutralize contaminants from polluted soil or water.

Point Sources [of Pollution] – single identifiable source of air or water pollution and that has negligible extent.

Porosity – The volume of pores in a soil sample (nonsolid volume) divided by the bulk volume of the sample.

Precipitate – Specific cations and anions combine to form a compound.

Reclamation – A set of activities practiced on disturbed lands such as those disturbed by mining or oil and gas drilling to limit erosion, maintain air and water quality, avoid surface and groundwater contamination, culminating in revegetation with suitable plant species.

Redox Concentrations – Zone where iron oxides have accumulated due to oxidation of reduced iron—high chroma mottles.

Redox Depletions – Zone where iron oxides coatings have been removed due to reduction of iron—low chroma mottles or matrix.

Redoximorphic – Morphology related to the reduction, oxidation and translocation of carbon, iron, manganese and sulfur.

Redoximorphic Features – Features or morphology related to the reduction, oxidation and translocation of carbon, iron, manganese, and sulfur.

Reduced Tillage – A tillage system in which the total number of tillage operations preparatory for seed planting is reduced from that normally used on that particular field or soil.

Reduction – Chemically, the gain of electrons by an element.

Residual Materials – Unconsolidated and partly weathered mineral materials accumulated by disintegration of consolidated rock in place.

Residue Management – The operation and management of crop land to maintain stubble, stalks, and other crop residue on the surface to prevent wind and water erosion, to conserve water, and to decrease evaporation.

Residuum – Unconsolidated, weathered, or partly weathered mineral material that accumulates by disintegration of bedrock in place.

Respiration – Metabolism of an organism resulting in release of energy and carbon dioxide.

Rhizobia – General term to identify root-nodule bacteria, such as rhizobium and bradyrhizobium, that are active in biological nitrogen fixation.

Rhizosphere – Zone of soil immediately adjacent to plant roots in which the kinds, numbers, or activities of microorganisms differ from that of the bulk soil.

Rill Erosion – An erosion process on sloping fields in which numerous and randomly occurring small channels of only several centimeters in depth are formed, occurs mainly on recently cultivated soils.

Riparian Buffer – A vegetated area (type of buffer strip) near a stream, usually forested, which helps shade and partially protect a stream from the impact of adjacent land uses. Riparian buffers have become common conservation practices designed to improving water quality and reducing pollution.

Riparian Zone – The above (vegetation) and below ground (soil) area adjacent to a water body typically a stream or river.

Saltation – A particular type of momentum-dependent transport involving: (i) the rolling, bouncing or jumping action of soil particles 0.1 to 0.5 mm in diameter by wind, usually at a height ?15 cm above the soil surface, for relatively short distances. (ii) The rolling, bouncing or jumping action of mineral grains, gravel, stones, or soil aggregates effected by the energy of flowing water. (iii) The bouncing or jumping movement of material downslope in response to gravity.

Saprolite – Chemically weathered rock that has not lost its original rock fabric or changed its volume but has lost some of its original mass—in other words it looks like rock but has a lower bulk density than unweathered rock and can be dug with a shovel.

Saprophyte – Any organism living upon dead or decaying organic matter.

Saturation – All the soil pores are filled with water.

Schematic Soil Map – A soil map compiled from scant knowledge of the soils of new and undeveloped regions by the application of available information about the soil-formation factors of the area.

Scientific Notation – Method used by scientists involving powers of 10 to work with very large or very small numbers.

Sheet Erosion – The removal of a relatively uniform thin layer of soil from the land surface by rainfall and largely unchanneled surface runoff (sheet flow).

Shifting Cultivation – Agricultural systems similar to long-term rotations, in which areas are cultivated for a few years until nutrients are depleted, then abandoned to be reclaimed by native vegetation. Cultivation moves to an adjacent area. Native vegetation restores some fertility so the area can be cultivated again ten or more years later.

Shrink–Swell Clays – Clay minerals that expand greatly when wet or saturated, e.g., montmorillinite, bentonite.

Silt Fence – An erosion control practice installed on the perimeter of construction sites to limit movement of eroded soil sediments off the construction site.

Silvopastoralism – Practices that combine management of livestock, forage crops and tree production in an integrated pasture system.

Single-Grained – A structureless soil condition where the particles are not aggregated. Non-cohesive materials.

Slime Mold – Fungus-like protists that during part of their life cycle when food is short can move in a gelatinous trail or “slime” pathway.

Sludge – Solids remaining after effluent (liquids) is removed during the wastewater treatment process. With additional treatment, sludges may be treated further to become biosolids.

Sodification – The process whereby the amount of exchangeable sodium in a soil is increased.

Soil – A natural, three-dimensional body at the earth’s surface. It is capable of supporting plants and has properties resulting from the effects of climate and living matter acting on earthy parent material, as conditioned by relief and by the passage of time.

Soil Map – A map showing the distribution of soils or other soil map units in relation to the prominent physical and cultural features of the earth’s surface. Five soil maps are recognized in the United States: detailed soil map, detailed reconnaissance soil map, generalized soil map, reconnaissance soil map, and schematic soil map.

Soil Moisture Regimes – Refers to the moisture content in the upper portion of the soil, they include Aquic, Aridic, Udic, Ustic, and Xeric types

Soil Order – A group of soils in the broadest category. For example, in the 1938 classification system. The three soil orders were zonal soil, intrazonal soil, and azonal soil. In the 1975 there were 10 orders, whereas in the current USDA classification scheme there are 12 orders, differentiated by specific characteristics or properties: Alfisols, Andisols, Aridisols, Entisols, Gelisols, Histosols, Inceptisols, Mollisols, Oxisols, Spodosols, Ultisols, Vertisols. Orders are divided into suborders and the suborders are further divided into great groups.

Soil Organic Matter – Component of soil that contains carbon and is living or once was living but now is in various states of decomposition.

Soil Quality – Generalized term used to describe a soil’s ability to properly function and sustain plant, animal, and microbial productivity and maintain or enhance air and water quality.

Soil Series – The lowest category of u.s. system of soil taxonomy. A soil series is named for the area in which it was first mapped. A soil series is based on specific morphological, physical and chemical properties that make it unique. It is equivalent to the species level in Linnaean classification.

Soil Survey – (i) the systematic examination, description, classification, and mapping of soils in an area; (ii) the program of the national cooperative soil survey that includes describing, classifying, mapping, writing, and publishing information about soils of a specific area.

Soil Taxonomy – U.S. Department of Agriculture–Natural Resource Conservation Service basic system of soil classification for making and interpreting soil surveys.

Soil Temperature Regimes – Refers to the average annual soil temperature at 50 centimeters (20 inches) below the soil surface. There are six different regimes: Gelic, Cryic, Frigid, Mesic, Thermic, Hyperthermic.

Spodosols – Acidic, sandy forest soils under conifers—sandy areas of the northeast to Minnesota, sandy areas of the Atlantic coastal plain.

Springtail – Six-legged mesofauna or macrofauna that feed on organic materials or other smaller organisms. Most in soil are too small to be seen with the unaided eye.

Strip Cropping – The practice of growing two or more crops in alternating strips along contours, often perpendicular to the prevailing direction of wind or surface water flow.

Structure – The combination or arrangement of primary soil particles into secondary units or peds. The secondary units are characterized on the basis of size, shape, and grade (degree of distinctness).

Structureless – No observable aggregation or no definite and orderly arrangement of natural lines of weakness. Massive, if coherent; single-grain, if noncoherent.

Surface Creep – (i) The rolling of dislodged soil particles 0.5 to 1.0 mm in diameter by wind along the soil surface. (ii) The slow movement of soil and rock debris which is usually not perceptible except through extended observation.

Suspension – The containment or support in fluid media (usually air or water) of soil particles or aggregates, allowing their transport in the fluid when it is flowing. In fluids at rest, suspension follows Stoke’s Law. In wind this usually refers to particles or aggregates ?0.1 mm diameter through the air, usually at a height of ?15 cm above the soil surface, for relatively long distances.

Sustainability – Managing soil and crop cultural practices so as not to degrade or impair environmental quality on or off site, and without eventually reducing yield potential as a result of the chosen practice through exhaustion of either on-site resources or non-renewable inputs.

Symbiotic Association – Relation between two different organisms where the activity of one affects the other. Three types exist: i. Parasitism—one benefits, other is harmed (ticks), ii. Mutualism—both benefit (i.e., Mycorrhizea), iii. Commensalisms—one benefits other unaffected

Taiga – A biome characterized by coniferous forests consisting mostly of pines, spruces, and larches.

Termitaria – Termite mounds.

Terrace – (i) A step-like surface, bordering a stream or shoreline, that represents the former position of a flood plain, lake, or sea shore; (ii) A raised, generally horizontal strip of earth and/or rock constructed along a hill on or nearly on a contour to make land suitable for tillage and to prevent accelerated erosion; (iii) An earth embankment constructed across a slope for conducting water from above at a regulated flow to prevent accelerated erosion and to conserve water.

Texture – The relative proportions of the various soil size separates in a soil.

Thermalism – The therapeutic use of hot-water springs.

Thermic – average annual soil temperature is higher than mesic, sometimes referred to as the cotton belt

Topsoil – (i) The layer of soil moved in cultivation. Frequently designated as the Ap layer or Ap horizon. See also surface soil. (ii) Presumably fertile soil material used to topdress roadbanks, gardens, and lawns.

Transformations – The process of chemical, physical or biological change of soil materials – when a component turns into a different component, such as through decomposition and/or weathering.

Translocations – The process of movement of soil materials within the soil—movement from one location in the soil to another (eluviation, illuviation).

transported materials – Parent materials that have been moved and deposit some distance from their point of origin.

Udic – soil is neither dry nor wet for long periods during the year

Ultisols – Acidic, strongly leached, older soils—common in the Southeastern United States and old piedmont landscapes worldwide.

Value – Relating to color, the degree of lightness or darkness of a color in relation to a neutral gray scale. On a neutral gray scale, value extends from pure black to pure white; one of the three variables of color.

Vertisols – Clayey soils that swell when wet—parts of Texas west to the desert southwest and east through Alabama, Mississippi delta region, northern great plains and parts of California. Also common in parts of India and Ethiopia.

Vesicle – Round or vase-shaped organelle of endomycorrhizae used mainly for storage of lipids.

Virus – Small particle that contains RNA or DNA and infects a living organism

Visual Deficiency Symptoms – Low nutrient levels in plants that cause abnormal growth or discoloration.

Waste Management – The collection, transport, processing or disposal, dispersal, managing and monitoring of municipal, industrial, food-processing, or animal wastes.

Water Control Structures – Small, adjustable dams placed in drainage ditches or irrigation canals to manage water levels.

Water Table – Top of the zone where all the pore in the soil are filled with water and water will flow due to gravity.

Water-Holding Capacity – The amount of water that a given material can hold after gravitation al water has been removed.

Xeric – soil has moist cool periods and warm dry periods.